ETMightWrite,NotRadiate

ChristopherRose1andGregoryWright2

1WINLAB

RutgersUniversity

Piscataway,NewJersey08854USA

2AntiopeAssociates

18ClayStreet

FairHaven,NewJersey07704USA

February24,2005

WriteNotRadiate1

Atruckfilledwithstoragemedia,drivenacrosstown,isaveryreliable

highbitratechannel.

–Comm.TheoryCollectiveSubconscious

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TenYearsofWirelessResearch

�SpectrumManagement

Interferencehurts,sodealwithit!

�Delaytolerance

–Transmitwhenchannelgood!

�Mobility

–Isnotanathema�ithelps!

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GOPOSTAL!�Radiointerferenceisbad

–Mutualinterferenceisanetworkkiller

�Mobilityisgood

–Canoftentoleratedelay

–Channelespeciallygoodwhennearby

�Storagedensityisincreasing

–FasterthanMoore!

�ForgetRadio!Writemessagedown!Tossittorecipient!

Completelyridiculous!!(right?)

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Nope,NotRidiculous�NYC/BostonMatterTransportEnergy

–200milesat20milespergallon

–1�2�108Joulespergallon

–100kgDVDs:�2�5�105bits/joule

�EquivalentRadiationEnergy

–Satellite:5660bits/joule(3�5�104kmuplink,D2propagation,1m2dish)

–Terrestrial(320km,D4propagation):MUCHlowerefficiency

Butadhoccomparisonsareunsatisfying

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ALittleAnalyticRigor

R2

π

0D

apertures

0Dr

τ=D/c+T

T

radiated message

D/c 0

Mass Transport

Radiation

mass delivered

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InformationDensity,ρ̃

HowAboutBlackHoles?

�SchwarzschildRadius:r�2GM�c2�1�5X10�27M

�Infocontentgoesaseventhorizonsurfacearea:1072r2bits

ρ̃�1�5�1045rbits/kg

�Microhole(1µmradius):1�5�1039bits/kg

�Donut-holesizedhole(1cmradius):1�5�1043bits/kg

Aweebitimpractical(andantisocial)

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EmpiricalMassInformationDensitiesI

VoyagerSpacecraft:106bits/kg

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EmpiricalMassInformationDensitiesII�20lbpaper@1000dpi:2�1010bits/kg

�DVD:3�1012bits/kg

�MagneticStoragewithFeO2:2�1017bits/kg

�OpticalLithographywithSiO2:3�85�1018bits/kg

�E-beamLithographywithSiO2:1�54�1021bits/kg

�STMwithXeonNi:1�74�1022bits/kg

�RNA:3�6�1024bits/kg

�LiBe:7�5�1025bits/kg

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MinimumTransportEnergy,E�

Justtheinitialkineticenergy:

E��12

mv̄2

.

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MinimumTransportEnergy,E�

Justtheinitialkineticenergy:

E��12

mv̄2

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InscribedMatterEnergyRequirements�MessagesizeB,massinformationdensityρ̃

Ew�

12

Bρ̃

v̄2�12

Bρ̃�

cδ�

2

10 101010100110864

solar escape

earth escapem

ilky way escape

jetliner

brisk walk

δ

light speed

�Artillery:addsafactorof2toenergy

�Escape:smallpenaltyifv̄�2�escapevelocity

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RadiationEnergyRequirements�Energycapture

ν�D��

AG

4πD2

�BitsalaShannon:

B�TC�TWlog2PGA

4πD2

N0W

�1

�Er�PT,

Er�BN04πD2

AGTWB�

2B

TW�1

�

�LargeTW:

ErBN04πD2

AGln2

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RadiationtoTransportEnergyRatio

Ω�ErEw

NormalizedAperture�A�2RλNormalizedDistance�D�D2R

Ωρ̃N0c2

8π2

DA

2

�2ln2�δ2

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IsotropicRadiationvs.TerrestrialArtillery

ρ̃�3�1024,R�5cm,Temperature300K

10-9

10-8

10-7

10-6

10-5

Fraction of Lightspeed10

0

102

104

106

108

1010

Ω

D=10mD=100mD=1000mD=10000m

walking

running

jetlinerAside:�250secondsbetweenNYCandBostonballistically

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ChiptoChipLaserLinks

D=10cm

2R=10um

300KIR

Laser

�Delay:δ�109

�Wavelength:λ�1µm

�Magneticstorage:Ω�104

�STMinscription:Ω�5�108

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Interstellar

(ρ̃�1022,δ�103,Temperature3K)

102

104

106

108

1010

1012

1014

1016

1018

1020

1022

D (normalized distance)

100

104

108

1012

1016

1020

A

(norm

alized ap

erture)

Arecibo@10GHz10m Optical (500nm)1m Xray (0.1nm)Earth@10GHz

Ω

1

10-6

106

1012

1018

1024

1030

�10kLY,Arecibo-Arecibo:Ω�5�1015–Radiation/Matter:(2megatonblast)/(Shelve5lbsugarbag)

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Voyager

�109bitpayload

�900kgmass

�Catapultlaunch:about800joules/bit

BreakevenDistance:2000lightyears

�Asides:

–RocketLaunch:distanceup�9.

–Use3DVDs(insteadofgolddisc):distancedown�10

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ThePhysicsHasSpoken

Matterisstunninglymoreefficientforawiderangeofdistancesandmethodsof

radiatedcommunications.

Butwhatabout...

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MatterandRadiationPenalties

�Radiation

–ImpermanenceandRepetition

�Matter

–Broadcast

–InscriptionEnergy

–DecelerationAtTarget

–Navigation

–Preservation

–Advertisement

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MatterPersists–RadiationVanishes

messageradiated

messageradiated

messageradiated

birthlife

time

radiatedmessage

mass packet

�CivilizationBirthRate:α�1�109peryear

�CivilizationExtinctionRate:β�1�106peryear

�Successcriterion0�Φ�1

�Howmanyradiatedrepetitions?

–Φ�0�99�2�105–Φ�0�9999�2�107

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IsRadiationBetterforBroadcast?

�Radiationilluminatesmany�matterpenalty

�MilkyWaystellardensity2�8�10�2stars(LY)�3

�Sphericalgalaxy,isotropicradiation,Arecibo-Arecibo

–R�104LY:1�13�1011stars(butΩ�1028)–R�106LY:1�13�1017stars(butΩ�1032)

No,inscribedmatterstillwins!

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InscriptionEnergy/Speed

�MatterInscription/ReadoutEnergyandTime

–Canbereversibleandabitrarilyfast(R.Landauer)

�Empiricalenergycalc:

–60000ATP/secondfor20minutes:4639KbaseofE-coli

–8�10�20JperATPmolecule–6�2�10�19Jbit�1.–E�atearthescape:1�68�10�17Jbit�1.

Constructionenergyprobablynotaproblem

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ParkingthePackage

�Assumeexhaustbraking

�Energypenalty(excessmass):ec

δgIsp

�Isp�SpecificImpulse

–Chemical:102

–NuclearElectric:104

–Fusion:106

�Isp�20�000,δ�1000�penalty4�6

�δ�100orIsp�2000�penalty4�4�106

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GravitationalPerturbations

AngularDeflection:θ�2MGv2

0y0(radians)

�M�2�1030kg(solar)

�v0�c�1000

�StellarDensity:2�8�10�2stars(LY)�3

�10kLYtripmeanmissdistance:�0�14LY

Aimnotabigproblem

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CosmicInsults�Insults:

–Highenergyparticlebombardment

–Heating(diffusion)

–Iontracks,dislocations,subatomiccascades

�Shielding:

–10millionyearsat10%bacteriaviability:3mradiusrock(3gcm�3density)

–3�4�106penalty

�CleverComposition,CodingandCorrection?

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OverallImplication

ETmightwritenotradiate

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SolarSpaceisBIG

MessageAdvertisement?

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BigRock?

Somewhatantisocial

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OddRock?

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SeededComet?

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ActiveProbe?

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LifeBoat?

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CONCLUSIONS

IfDelayAcceptable

�Inscribedmattermessagingisefficient

–FedExandNetflix

�MightevenfinesseGupta-Kumaradhocnets�Nproblem

–littledatamissiles

�Chip-to-chipormote-to-motecommunication

–smartdusttossinginscribeddust

�Shouldstartlookingforextraterrestrialartifacts

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LearnMore

Nature431,pp.47–49,September2,2004WebSite:http://www.winlab.rutgers.edu/�crose/cgi-bin/cosmic18.html

C.RoseWINLABUTSA